Tiffany Hagler-Geard | Bloomberg | Getty ImagesShares of DocuSign tanked 18% in trading Friday, a day after the e-signature provider reported stronger-than-expected earnings but slashed its full-year billings outlook.Here's how the company performed in its fiscal first quarter, compared with estimates from analysts polled by LSEG:Earnings per share: 90 cents, adjusted, vs. 81 cents expectedRevenue: $764 million vs. $748 million expectedBillings, a closely watched sales metric, came in at $739.6 ...